Auxiliary venturi vacuum adapter for vacuum controlled spark advance



May 23, 1950 A T To ENE)- 1 l & m \w m g T 8 N N. 0 RN M Z ml 2 a 0 w it m \m 0m 5 @N I C 8n G. YOUNG ETAL AUXILIARY VENTURI VACUUM ADAPTER FOR Filed Aug. 'a1, 1946 Ganfh [Jfiuny and William VACUUM CONTROLLED SPARK ADVANCE i atentecl May 2 3, 1950 AUXILIARY VENTURI VACUUM ADArrEa FOR VACUUM CONTROLLED SPARK AD- VANCE Garth 'L. Young and William Ostling, Los Angeles, -Galif., assignors to California Machinery and SupplyCo. -Ltd., Los Angeles, Calif., a corporationof Delaware Application August 31, 1946, Serial No. 69.4 266 10 Claims.

This invention relates to a spark control mechanism 'for spark ignition internal combustion motors.

This invention is an improvement upon the spark control mechanism and method of the 'Vand'erpoel et a1. Patent No. 2,249,446, and other similar spark control devices and methods.

In such methods the advance of the spark is ;,controlled to respond to the joint action of the avacuum at the throttle and at the Venturi.

The fuel induction system carries an orifice positioned at the throttle so that it is on the .carburetor side of the throttle in idling posi- \tion .and on the manifold side of the throttle awhenthe throttle is in part open position. An- ;other orifice is placed at the Venturi throat of :the carburetor; a tube connected to both orifices is in turn connected to a chamber in the disatributor in which a diaphragm is placed; and the :diaphragm moves a rod which causes an adjustment of the spark advance in the distributor.

.In this fashion the advance responds to the vacuum as generated atthe throttle orifice modifie'd' by the vacuum generated at the Venturi orifice.

The vacuum generated at the Venturi throat for any given air'ilow resulting from the pumping 'efiect of the engine at any given R. P. is limited by .the discharge coefiicient of the Venturi. This discharge coefficient for carburetors substantially is less'than can be obtained from a well designed Venturi, because of the effect of the fuel nozzles. Fuelinjected through the nozzles, chokes and throttles introduces fluid friction in the Venturi" throat and on both sides ofthe Venturi throat. Thus, even for the most efiicient of commercial types .of carburetors the discharge coefiicient is rarely greater than about .8.

The improvement. of this .invention consists broadly in introducinga second "Venturi ahead of the carburetor'venturi and ahead "of thefuel injection point andplacing the..Venturi. orifice atthis auxiliary'venturixinstead of at the carburetor Venturi. Comparedwith a, dischargecoefiicient of about 48 for'a conventional carburetor Venturi, we can, byemploying a well designed venturi iree of such "fluid friction creating devices, obtain adischarge,.coefiicient substantially greaterthanrfiand as much as .95 or greater. ,By employing anauxiliary venturi and placing the Venturi Orifice at such Venturi instead of'the carburetor; Venturi, we may obtain for'the'same airflowaymaterially lower, pressure same air flow when the Venturi orifice is located in the carburetor venturi.

The result of this modification is that the influence of the Venturi orifice upon the spark setting is magnifiedabove that which the Venturi orifice has in the prior art devices. This is particularly true under the conditions of road'load or full load where the prior art devices operate to cause too great a retardat road loadand at full load operations. With the improvement of our invention the spark advance at full load and at road load conditions more closely approximates engine requirements at these load conditions for optimum horsepower output.

In such systems where, as is usual, a choke valve is placed ahead of the carburetor Venturi, when the choke is closed, as, forexample, during starting or idling, the pressure in the Venturi orifice and at thethrottle orifice maygfall so low as to cause an undesirable advance of the spark. In order to avoid thispossibility, the prior art has employed various expedients for insuring-that the spark would be held retarded during idling or cranking when the choke was closed. In our device, due ,to the 'fact that on closing of the choke the Venturi orifice is on the atmospheric pressure side of the choke, a highpressure is exerted at the Venturi orifice, and, even though the pressure at the throttle orifice 'falls toaloW level, the Venturi orifice bleeds into the diaphragm chamber to insure that ,thespark is retarded.

This invention and its objects will be further described in connection with the drawings, in which:

Fig. l is arview in part section of the carburetor and spark. advance mechanism of our invention; and

Fig. 2 shows a de system of,Fig.,1.

The carburetor is connected at flange 2 to the engine manifold of ,a conventional sparlrignition internal combustion motor. The carburetor contains the conventional air induction tube I, the throttle '3, Venturi 4, carrying a-fuel injection nozzle'5 and a choke 6, as conventional.

Mounted on shoulder I is the aux iliary venturi 8 of our invention. The Venturi section can ries an external shoulders on which is mounted an air, cleaner ill and the assembly held ,inplace by means of clamping ring Ii and ear I la. This Venturi .is preferably positioned so that its discharge coefficient, is not iinfiuenced' by the iriptional eifects of the carburetor or choke or the tail. of one modification of the atthe-Venturi orificethamisobtainable-for the air-cleaner. "It isdesired to make its constants,

such as throat diameter and streamlining, such as to give the maximum vacuum at the attained rate of air flow. For this reason it is placed sufiiciently away from the air cleaner and ahead of the choke to give maximum efficiency.

Positioned at the throttle 3 is an orifice l3 and bore l4 drilled in the boss l2 so that the orifice i3 is on the carburetor side of the throttle 3 when the throttle is in cranking or idling position and on the manifold side when the throttle is in road load, i. e., part open position.

In the bore 14 fitting is received. The fitting [5 has a conduit [6 which is connected to tube I! by a fitting 18.

A second orifice I9 is positioned at the throat or vem contracti of the venturi 8. In the conical bore 20 is screwed a fitting 2| having a cross bore 22 coaxial with 20 and a cross bore 23 to which the tube 11 is connected bymeans of fitting 24. The bore 22 is connected to tube 26 by means of fitting 25.

The spark setting and distributors device 27 is conventional except for the following modification. It is provided with a cam 28 of usual design operating on shaft 23. Around the shaft is rotatably mounted a breaker plate 33 carrying a conventional breaker 30a. This breaker plate, in order to adapt it to our invention, is formed with an upstanding pin 3% and a bore 31 through which protrudes a pin 32 positioned on an adjustable plate 33 mounted in the casing of the distributor 21 beneath the breaker plate 38. A spring 34 is mounted on pins 3% and 32. The rod 35 is connected to the plate 36 by hinge 36 and to the diaphgram 3i positioned in the airtight chamber 39 formed by cover 38. The tube 26 is connected to the chamber 39 by a fitting 43.

While we have described one form of device, other forms may be readily adapted to this use, as will be understood by those skilled in the art.

Fig. 2 shows a modified fitting to take the place of fitting l5 of Fig. 1. The tube 42 is screwed into the bore [4 and into the fitting 41 carrying a valve chamber 43 in which is positioned the spring 45 and ball check valve M which seats against the fitting 45 to close the conduit 41.

The operation of the vacuum controlled spark advance, as shown in Fig. l, is as follows:

Engine at rest: When the engine is at rest, atmospheric pressure exists above and below the diaphragm 31 and the spring 34 moves the breaker plate to .full retard position.

Cranking: While cranking the throttle is at idling position, as shown in Fig. 1; the flow of air through the venturi 8 past the orifice l9 and also past the orifice i3 is low; and a relatively high pressure exists in the conduits 20, I4, and 26 and chamber 39. The degree of vacuum thus generated in chamber 39 is insufficient to move the diaphragm with a force suflicient to overcome the tension in spring 34 and the spark remains in full retard position. The closing of the choke valve 6 will cause the pressure at the Venturi orifice l9 to rise, thus insuring that the spark will remain retarded during cranking even though the choke is closed or partly closed.

Idling: As the motor speeds up to idling speed, the throttle remains in cranking position, as shown in Fig. 1. There is an increase in the rate of flow of air past the orifices I9 and [3 but insufiicient to create a vacuum in line 26 and chamber 39 and sufficient to overcome the tension in spring 34, and the spark remains in full retard position. The part closing of the choke 4 in this operation acts as in the case of cranking, thus insuring the retarding of the spark during idling even though the choke is closed or partly closed.

Road load conditions.As the throttle is opened wider to part throttle position, the throttle orifice l3 is placed on the manifold side of the throttle. The air flow increases, resulting in a decrease in the pressure on the throat of the venturi. The pressure at the throttle orifice 13 drops substantially to the intake manifold vacuum. The vacuum in lines I? and 26 is not, however, that of the manifold vacuum, since the pressure in the Venturi throat 8 is greater than the manifold vacuum. There is therefore an air bleed via I9, 20, and i1, causing the pressure in the line 26 to reach some pressure intermediate that of the pressure at 19 and 13. The reduction in pressure in 39 causes the diaphragm 68 to move the rod 35 and rotate the breaker plate 33 against the spring 34 to adjust the angular relation of the breaker plate and cam and advance the spark.

It will be observed that the advance effected is less than would be obtained where the tube 23 is connected to 13 only (i. e., in the absence of orifice It) by the bleeding efiect of the orifice [9. This prevents the over advance of the spark at road load conditions.

Comparing the effect of positioning the orifice 19 at 3 instead of at the throat 4, as in the prior art, it will be seen that since the discharge.

coefficient of venturi 4 is usually about to of the attainable discharge coeificient of B, the pressure in the throat of 4 is considerably greater for like air speeds than that attainable at the throat of 8. Therefore, the vacuum attained in tube 23 is greater than would be attained for the same throttle setting where the orifice is at the throat of 4. This means that the spark advance will be greater for the same engine speeds.

Full load conditions.-As the throttle is opened wider to full throttle position the pressure in the intake manifold rises and the pressure at the orifice I3 is then greater than at the throat of the venturi 8. The direction of the air bleed is therefore from I3 through I! into 22, to modify the vacuum created by the air fiow through the venturi 3. The pressure in the tube 23 is higher than at part throttle operation and the distributor moves to part retard.

It will be observed that here also the increased vacuum in the throat of 8 as compared with that attainable in 4 causes the pressure in 26 to be lower than it would have been where the orifice i9 is at 4 and the spark is prevented from being over retarded.

The operation of the device as modified in Fig. 2 is as follows:

Engine at rest-The conditions are similar to those described above. The check valve is seated as in Fig. 2.

Cranking.There is insufiicient difference in pressure to unseat the ball 44. The operation is as described above in connection with Fig. 2.

Idling-The pressure difference is sufficient to unseat the valve, and the operation is similar to that described above in connection with Fig. 2.

Road Zoad.--The pressure in I! modified by the higher pressure at I9 is higher than at I 3, the ball remains unseated, and the operation is as described above in connection with Fig. 2.

Full load condition.Since in this condition the pressure at 13 is greater than at IS, the ball.

amascr seats and the tube 26 is subjected to the vacuum at l9. Since this is now unmodified bythe pressure at [3, the vacuum in 26. is higher for the same position of the throttle and a greater degree of spark advance is obtained than that obtained for Fig. 1.

While we have described aparticular embodiment of our invention for the: purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims;

, We claim:

1. In combination, an ignition timer and carburetor for an internal combustion motor, comprising an air intake passageway, a venturi in said passageway, an air discharge conduit from said venturi, a carburetor, a carburetor venturi, an associated fuel injection nozzle, an air inlet to said carburetor venturi connected to said first- 2,0

mentioned venturi, a fuel and air discharge conduit from said carburetor, a throttle in said air and fuel discharge conduit, means for attaching said air and fuel discharge conduit to the manifold of an internal combustion engine, an 5 orifice in the throat of said first-mentioned venturi and an orifice at said throttle, said orifice at said throttle being positioned so that it is on the carburetor side of the throttle when the throttle is in idling position and on the manifold 0 side of said throttle when the throttle is in part open position, a by-pass conduit connected to both of said orifices, an ignition timer, a pressure responsive device for advancing and retarding the spark advance setting of said ignition timer,

prising an air intake passageway, a venturi in said passageway, an air discharge conduit from said venturi, a carburetor, a carburetor venturi, an associated fuel injection nozzle, an air inlet to said carburetor venturi connected to said firstmentioned venturi, a fuel and air discharge conduit from said carburetor, a throttle in said air and fuel discharge conduit, means for attaching said air and fuel discharge conduit to the manifold of an internal combustion engine, an orifice in the throat of said first-mentioned venturi and an orifice at said throttle, said orifice at said throttle being positioned so that it is on the carburetor side of the throttle when the throttle is in idling position and on the manifold side of said throttle when the throttle is in part open 66 position, a by-pass conduit connected to both of said orifices, an ignition timer comprising a cam, a breaker arm operated by said cam, a cam shaft upon which said cam is mounted, means for adjusting the advance of said spark by adjusting the angular relationship of said cam and arm comprising an arm for moving said breaker arm relative to said cam, a diaphragm connected to said arm, a chamber in which said diaphragm is mounted, said by-pass conduit being connected 55 to said chamber.

3. In the device of [claim 1, a check valve in said by-pass conduit between the throttle orifice and said Venturi orifice and the point of connection of said by-pass conduit and said pressure 70 responsive device, said check valve being closed when the pressure at the throttle orifice is greater than at the Venturi orifice.

4. In the device of claim 2, a check valve in said by-pass conduit between the throttle orifice and said Venturi orifice andv the point of connection of said by-pass conduit and saidchamber, said check valve being closed when the pressure. atthe throttle orifice is greater than at the Venturi orifice.

5. A carburetor for an internal combustion engine, comprising an air intake passageway, a venturi in said passageway, an air discharge con-'- duit from said venturi, a second venturi in said passageway, a fuel injection nozzle associated, with said second venturi, an air inlet to said passageway connecting. said first mentioned ven turi and said second. mentioned venturi, a fuel and air discharge. conduit from said second venturi, a throttle in said air and fuel discharge conduit, means for attaching said air and fuel discharge conduit to the manifold of an internal combustion engine, an orifice in the throat of said first-mentioned venturi, an orifice in the wall of said conduit at said throttle, said orifice being positioned so that it is on the fuel injection side of said throttle when said throttle is in idling position and on the manifold side of said throttle when said throttle is in part open position, a by-pass conduit connected to both of said orifices, and means for connecting said by-passconduit to an ignition timer.

6. In the device of claim 5, a check valve in said by-pass conduit between the throttle orifice and said Venturi orifice and the point of connection of said by-pass conduit to said ignition timer.

7. A carburetor for an internal combustion engine, comprising an air passageway, a fuel injection nozzle in said passageway, an air fuel outlet from said passageway, an air inlet to said passageway, a throttle in said passageway on the discharge side of said passageway, a choke valve positioned in said passageway near the air inlet side of said passageway, said fuel injection nozzle being positioned between said choke and said throttle, a venturi in said passageway, said choke being positioned in said passageway between said venturi and said fuel injection nozzle, an orifice at the throat of said venturi, an orifice at said throttle, said orifice at said throttle being positioned so that it is on the fuel injection side of the throttle when the throttle is in idling position and on the manifold side of said throttle when the throttle is in part open position, a by-pass conduit connecting both of said orifices, and means for connecting said by-pass conduit to a pressure-responsive ignition timer.

8. In the device of claim '7, a check valve in said by-pass conduit between said throttle orifice and said Venturi orifice and the point of connection of said by-pass conduit to said pressureresponsive ignition timer.

9. A combination of an ignition timer and a carburetor for an internal combustion engine, comprising an air intake passageway, a venturi in said passageway, an air discharge conduit from said venturi, a fuel injection nozzle in said carburetor, a fuel and air discharge conduit from said carburetor, a throttle in said air and fuel discharge conduit, a choke valve between said venturi and said fuel injection nozzle, means for attaching said air and fuel discharge conduit to the manifold of an internal combustion engine, an orifice in the throat of said venturi, an orifice at said throttle, said orifice at said throttle being positioned so that it is on the carburetor side of the throttle when the throttle is in idling position and on the manifold side of said throttle when said throttle is in part open position, a bypass conduit connected to both of said orifices,

setting of said ignition timer, said last-named conduit being also connected to said pressureresponsive device.

10. In the device of claim 9, a check valve in said by-pass conduit between the throttle orifice and said Venturi orifice and the point of connection of said by-pass conduit and said pressure-responsive device, said check valve being closed when the pressure at the throttle orifice is greater than at the Venturi orifice.

. GARTH L. YCUNG.

WIILIAM OSTLING.

EEFERENoEs oi'riafi The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,084,158 Meade June 15, 1937 2,093,524 Meade Sept. 21, 1937 2,249,446 Vanderpoel et al. July 15, 1941 2,268,490 Mallory Dec. 30, 1941 2,270,982 Vanderpoel et al. Jan. 27, 1942 2,317,885 Colvin Apr. 2'7, 1943 2,365,313 Udale Dec. 19, 1944 

